====== LU04.A07 - ERD: Reingineering of an existing database  ======
From time to time, we may need to analyze an existing database in order to optimize the structure, e.g. for the next software version.

===== Prerequisites  =====
  * Work type: Peer
  * Means of aid: [[https://www.w3schools.com/sql/trysql.asp?filename=trysql_editor | W3Schools-SQL-Editor]]
  * Timeframe: 45 Minutes
  * Expected result: ERD as a PDF-File, that describes the content of the given date-base in Crow's Foot Notation.

===== Task  =====
Go to the W3Schools-Website, to the SQL-Editor, and analyze the existing data-structure. Create furthermore an ERD, that describes the existing data-structure in the Crow's Foot Notation.

{{:modul:m290:learningunits:lu03:aufgaben:screenshot_2024-09-12_151200.png?800| Given data-struture of W3Schools-SQL database}}

  - Identify all enties.
  - Add the attributes and the corresponding data-types to each entity.
  - Relate the tables to each other by analysing the primary keys and the foreign keys.

===== Solution =====
[[modul:m290:learningunits:lu03:loesungen:l07|Lösung]]

===== Vocabulary =====
^ English ^ German ^ 
| prerequisite | Grundvoraussetzung |
| given| gegebene, vorausgesetzt |


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[[https://creativecommons.org/licenses/by-nc-sa/4.0/|{{https://i.creativecommons.org/l/by-nc-sa/4.0/88x31.png}}]] Volkan Demir